利用SMTPLibrary后台发送邮件

话不多少，直接代码，先添加头文件和代理 SKPSMTPMessageDelegate

#import "SKPSMTPMessage.h"
#import "NSData+Base64Additions.h"
/**
  email  接收方邮箱
  shareImage 附件图片
  title 标题
  content 内容
*/
-(void)sendEmailMsg:(NSString *)email shareImage:(UIImage *)shareImage title:(NSString *)title content:(NSString *)content{

NSMutableDictionary *defaultsDictionary = [NSMutableDictionary dictionaryWithObjectsAndKeys:@"fromEmail@fromEmail.com.cn", @"fromEmail",
                                           email, @"toEmail",
                                           @"smtp.exmail.qq.com", @"relayHost",
                                           @"fromEmail@fromEmail.com.cn", @"login",
                                           @"fromEmailPwd", @"pass",
                                           [NSNumber numberWithBool:YES], @"requiresAuth",
                                           [NSNumber numberWithBool:YES], @"wantsSecure", nil];

SKPSMTPMessage *testMsg = [[SKPSMTPMessage alloc] init];
testMsg.fromEmail = [defaultsDictionary objectForKey:@"fromEmail"];
testMsg.toEmail = [defaultsDictionary objectForKey:@"toEmail"];;
testMsg.relayHost = [defaultsDictionary objectForKey:@"relayHost"];
testMsg.requiresAuth = [[defaultsDictionary objectForKey:@"requiresAuth"] boolValue];
if (testMsg.requiresAuth) {
    testMsg.login = [defaultsDictionary objectForKey:@"login"];
    testMsg.pass = [defaultsDictionary objectForKey:@"pass"];  
}
testMsg.wantsSecure = [[defaultsDictionary objectForKey:@"wantsSecure"] boolValue]; // smtp.gmail.com doesn't work without TLS!
NSString *txt = content;
testMsg.subject = title;
testMsg.delegate = self;
NSDictionary *plainPart = [NSDictionary dictionaryWithObjectsAndKeys:@"text/plain; charset=UTF-8",kSKPSMTPPartContentTypeKey,txt,kSKPSMTPPartMessageKey,@"8bit",kSKPSMTPPartContentTransferEncodingKey,nil];
if (!shareImage) {
    testMsg.parts = [NSArray arrayWithObjects:plainPart,nil];
}else{
    NSData *vcfData = UIImageJPEGRepresentation(shareImage, 0.5);
    NSString *str1 = [NSString stringWithFormat:@"text/directory;\r\n\tx-unix-mode=0644;\r\n\tname=\"report.png\""];
    NSString *str2 = [NSString stringWithFormat:@"attachment;\r\n\tfilename=\"report.png\""];
    NSDictionary *vcfPart = [NSDictionary dictionaryWithObjectsAndKeys:str1,kSKPSMTPPartContentTypeKey,
                             str2,kSKPSMTPPartContentDispositionKey,[vcfData encodeBase64ForData],kSKPSMTPPartMessageKey,@"base64",kSKPSMTPPartContentTransferEncodingKey,nil];
    testMsg.parts = [NSArray arrayWithObjects:plainPart,vcfPart,nil];}
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
    [testMsg send];
});}

回调如下：

  - (void)messageSent:(SKPSMTPMessage *)message{
 NSLog(@"邮件已发送，请注意查收");
  }

- (void)messageFailed:(SKPSMTPMessage *)message error:(NSError *)error{
NSLog(@"发送失败，请重试");
}

注意事项
SMTPLibrary是运用的MRC，所以在ARC需要在targets下 选择BuildPhases下找到SKPSMTPMessage 和 NSStream+SKPSMTPExtensions 文件添加 -fno-objc-arc 即可。